How To Troubleshoot Disconnecting Uplink?

[QuikeyMan_2]

I have two Catalyst 3570 switches, switch A and switch B, connected via GBICs in uplink ports.  The ports are randomly disconnecting, so I am suspecting that one of the mini GBICs is failing, but I cannot figure out which one.  Is there a way to figure which GBIC is the culprit?  Switch A has another GBIC going to another switch, and that connection has not failed, so I am thinking the issue is either with switch B itself, or one of the GBICs connecting switch A and switch B.  The odd thing, to me at least, is that once the connection has failed, I can take the GBIC out of either switch, put it in another uplink port, reconnect the fiber, and the connection is restored.  If I take the GBIC back in the same uplink port, the connection is not restored.

[Reza Sharifi]

If the you put the bad GBIC in another port and it works fine then the GBIC is most likly not bad.  Have you tested the fiber patch cord between the switches?  The tips maybe dirty and you may want try cleaning them with a little alcohol.

Or you can try a different patch cord in you have one extra.

HTH

[QuikeyMan_2]

I did not even think about cleaning/swapping out the fiber patch cords.  Switch B is in a high dust environment, so that is likely where I will start.  The randomness of the disconnections did not make sense to me as I assumed that if it were a GBIC or switch, it would fail outright. 

[QuikeyMan_2]

I cleaned the existing fiber patch cables with some rubbing alcohol, but the connection was still dropping.  I then swapped out the fiber patch cables for a new pair, and the connection continued to drop.  I have a spare switch that I can swamp switch B out with, but it is not Cisco, and I am waiting on a compatible GBIC, which should be delivered Monday.